1. Field of the Invention
This invention relates to a control apparatus for an internal combustion engine, including engine-rotation-direction detection means for detecting the rotation direction of the engine on the basis of the outputs of a first crank angle sensor and a second crank angle sensor which are disposed so as to have a predetermined output phase difference therebetween.
2. Description of the Related Art
In recent years, there has been developed the technology of so-called “idle stop” wherein, for the reduction of fuel consumption, the suppression of a CO2 exhaust quantity, etc., an engine is once stopped automatically in an idling mode, and the engine is thereafter restarted automatically when a restarting condition such as car starting manipulation has held.
As a starting device suitable for the restarting of the idle stop, there has been known a technique wherein fuel is fed into the specified cylinder of the engine in a stop state and is ignited and combusted, and the engine is reversed once, thereby to bring the other cylinders substantially into compression states, and the fuel is thereafter fed into the engine and is ignited and combusted, whereby the restartability of the engine is enhanced (refer to, for example, JP-T-2003-515052, where the term “JP-T” means a published Japanese translation of a PCT patent application).
In such a technique, the phases of the pistons of the respective cylinders at stopping and restarting the engine need to be accurately detected. For this purpose, it is indispensable to accurately detect the reverse rotation of the engine attributed to a rotational inertial force immediately before the stop of the engine, and the rotation direction of the engine at the restarting.
As a rotation-direction detection device suitable for the detection of the engine rotation direction, there has been known a technique wherein the rotation direction of the engine is detected while taking note of the fact that the output patterns of two crank angle sensors disposed so as to have a predetermined output phase difference differ between in an engine forward mode and in an engine reverse mode (refer to, for example, JP-A-2005-2847).
In actuality, however, a situation where the output pattern of the crank angle sensors changes in spite of the non-change of the engine rotation direction occurs on account of the mounting errors of the crank angle sensors, the machining error of teeth to-be-detected, the component errors of a crank-angle-sensor output acceptance circuit, a measurement error ascribable to the running state of the engine, sensor characteristics, and so forth. In such a case, with a method wherein the change of the engine rotation direction is decided whenever the output pattern of the crank angle sensors has changed, as in the prior-art rotation-direction detection device disclosed in JP-A-2005-2847, the rotation direction of the engine is erroneously detected to worsen the restartability of the engine, and moreover, the engine might be damaged.